1. Field of the Invention
The present invention relates to an apparatus and method for processing a thin-film magnetic head material that are used for polishing a thin-film magnetic head material having a row of sections to become sliders each of which includes a thin-film magnetic head element.
2. Description of the Related Art
In general, a flying-type thin-film magnetic head used in a magnetic disk drive or the like is constituted by a slider having a thin-film magnetic head element at a rear end thereof. In general, the slider has a rail section whose surface serves as a medium facing surface (an air bearing surface) and a tapered section or step portion in the vicinity of the end on an air inflow side thereof. The rail section is slightly floated above the surface of a recording medium such as a magnetic disk by a stream of air that flows in through the tapered section or step section.
In general, such sliders are manufactured by cutting a wafer in one direction, the wafer having a plurality of rows of sections to become sliders (hereinafter referred to as slider sections) each including a thin-film magnetic head element. Materials referred to as xe2x80x9cbarsxe2x80x9d on which the slider sections are arranged in a row are thereby formed. The bars are then cut into sliders. A surface of a bar which is to become a medium facing surface (hereinafter referred to as xe2x80x9cmedium facing surfacexe2x80x9d for convenience) is subjected to processes such as lapping and formation of a rail portion. Such process may be performed before or after the formation of the bar.
In the process of manufacturing a slider as described above, the ultimate thickness of the slider or the profile of the medium facing surface may be controlled by lapping the surface of the bar opposite to the medium facing surface before or after the processing of the medium facing surface of the bar, or by lapping two surfaces of a block in which two rows of slider sections are arranged such that the medium facing surfaces thereof face each other, the two surfaces of the block being opposite to the medium facing surfaces.
Two methods as described below have been available for lapping the surface of the above-described thin-film magnetic head material as described above opposite to the medium facing surface (hereinafter referred to as xe2x80x9cback surfacexe2x80x9d).
A first method is to lap the back surface before lapping the medium facing surface. This method is primarily employed when a material in the form of a block is used in which two rows of slider sections are arranged such that the medium facing surfaces face each other. When such a material is used, a double-side lapping apparatus is frequently used to lap both sides of the material.
A second method is to lap the back surface after lapping the medium facing surface. This method is employed when using a bar formed by cutting a wafer in one direction, in which a plurality of rows of slider sections are aligned and oriented, for example, in the same direction. This method is often conducted by bonding the back surface of the bar to an appropriate jig, lapping the medium facing surface of the bar, removing the bar from the jig thereafter and bonding the medium facing surface of the bar to the jig to lap the back surface of the bar.
In either of the above-described two methods, the process (lapping) must be controlled such that the thickness of the material which is a workpiece attains a desired value. In order to control the thickness of the material, the processing time is controlled, for example, in prior art. Referring to the processing operation in such a case, the operator measures the thickness of the material and accordingly sets a processing time in the processing apparatus. In order to improve accuracy in processing, after starting the processing operation the operator measures the thickness of the material and adjusts the processing time once or more times by interrupting the process each time.
Recently, there are needs for compact sliders which are floated by only a small amount in order to achieve high density recording. The accuracy of the thickness of a thin-film magnetic head material has a significant influence not only on the accuracy of the thickness of the slider but also on the accuracy of the formation of a rail on the slider. Therefore, in order to provide a compact slider which is floated by only a small amount, the thickness of the thin-film magnetic head material must be accurately controlled.
In the case of above-described method in which the back surface of the thin-film magnetic head material is processed by controlling the processing time, however, the processing accuracy is low because there is significant variation in processing depending on the state of the surface plate, slurry and the like and on the operator. This results in a problem in that it is difficult to accurately control the thickness of the thin-film magnetic head material. Further, it has a problem in that an operator must repeat the measurement of the thickness of the material and processing of the same many times to improve processing accuracy, which increases the number of steps and reduces operating efficiency.
Especially, when the back surface of the bar is lapped after lapping the medium facing surface, the above-mentioned reduction in operating efficiency is significant because there are increased number of lapping steps compared to lapping of both sides of a material in the form of a block in which slider sections are arranged in two rows. Further, when the back surface of the bar is lapped after lapping the medium facing surface thereof, the measurement of thickness of the material and processing of the same repeated many times result in a problem in that the lapped medium facing surface may deteriorate and in that a thin film such as a GMR (giant magnetoresistive) film may be broken by electrostatic discharge (ESD).
It is a first object of the invention to provide an apparatus and a method for processing a thin-film magnetic head material which make it possible to improve the accuracy and efficiency of a process of polishing the material.
In addition to the first object, it is a second object of the invention to provide an apparatus and a method for processing a thin-film magnetic head material which make it possible to polish the surface of the material opposite to the medium facing surface thereof while protecting the medium facing surface.
An apparatus for processing a thin-film magnetic head material according to the invention comprises:
a processing machine which performs a polishing process on a thin-film magnetic head material in which sections to become sliders each including a thin-film magnetic head element are arranged in a row;
a first detector which detects a reference position;
a second detector which detects a position which changes depending on the thickness of the material; and
a controller which recognizes the thickness of the material based on the reference position detected by the first detector and the position detected by the second detector and controls the processing machine such that the thickness of the material becomes a predetermined value.
In the apparatus according to the invention, the first detector detects the reference position; the second detector detects the position which changes depending on the thickness of the material; and the controller recognizes the thickness of the material based on the positions detected by the two detectors and controls the processing machine such that the thickness of the material becomes the predetermined value.
In the apparatus according to the invention, the processing machine may have a rotating surface plate, and the apparatus may further comprise a processing jig for holding the material such that a surface of the material to be polished is put into contact with the surface plate.
The processing jig may hold the material having a band-shaped protective member applied to a surface thereof opposite to the surface to be polished. The processing jig may have: a first member having a hole at a lower end thereof, the hole allowing the material to pass therethrough and disallowing the protective member to pass therethrough; and a second member coupled to the first member, the first and second members sandwiching the protective member therebetween.
The first member may have a plurality of the holes described above. As the first member, a plurality of types of the first members may be provided which are different from each other in at least either the length or position of the hole thereof. The position of an outermost end of the hole may be uniformly set for the plurality of types of the first members.
In the apparatus according to the invention, a plurality of types of processing jigs may be provided as the processing jig described above, each of the processing jigs having a position regulating section for placing the material in a predetermined position. The jigs are different from each other in at least either the length or position of the position regulating section thereof. The position of an outermost end of the position regulating section is uniformly set for the plurality of types of the jigs.
In the apparatus according to the invention the first detector and the second detector may be mounted on the same arm.
In the apparatus according to the invention, the first detector and the second detector may intermittently perform the detecting operation.
In the apparatus according to the invention the controller may recognize the thickness of the material based on the result of detection carried out plural times by the first detector and the second detector.
A method according to the invention is provided for processing a thin-film magnetic head material, utilizing an apparatus for processing a thin-film magnetic head material that has: a processing machine which performs a polishing process on a thin-film magnetic head material in which sections to become sliders each including a thin-film magnetic head element are arranged in a row; a first detector which detects a reference position; and a second detector which detects a position which changes depending on the thickness of the material. The method comprises the steps of:
detecting a reference position using the first detector and detecting a position which changes depending on the thickness of the material using the second detector;
recognizing the thickness of the material based on the reference position detected by the first detector and the position detected by the second detector; and
performing the processing by controlling the processing machine based on the recognized thickness of the material such that the thickness becomes a predetermined value.
In the method according to the invention, the processing machine may have a rotating surface plate; and the material may be held using a processing jig such that a surface of the material to be polished is put into contact with the surface plate in the step of performing the processing.
In the method according to the invention, the processing jig may hold the material having a band-shaped protective member applied to a surface thereof opposite to the surface to be polished; and the processing jig may have: a first member having a hole at a lower end thereof, the hole allowing the material to pass therethrough and disallowing the protective member to pass therethrough; and a second member coupled to the first member, the first and second members sandwiching the protective member therebetween.
The first member may have a plurality of holes described above. As the first member, a plurality of types of the first members may be provided which are different from each other in at least either the length or position of the hole thereof. The position of an outermost end of the hole may be uniformly set for the plurality of types of the first members.
In the method according to the invention, a plurality of types of processing jigs may be provided as the processing jig described above, each of the processing jigs having a position regulating section for placing the material in a predetermined position. The jigs are different from each other in at least either the length or position of the position regulating section thereof. The position of an outermost end of the position regulating section is uniformly set for the plurality of types of the jigs.
In the method according to the invention, the first detector and the second detector may be mounted on the same arm.
In the method according to the invention, the detecting steps may intermittently detect the positions.
In the method according to the invention, the recognizing step may recognize the thickness of the material based on the result of detection carried out plural times by the first detector and the second detector.
Other objects, features and advantages of the invention will become sufficiently apparent from the following description.